Electromagnetic signal modification in a localized high-speed plasma flow:Simulations and experimental validation of a stationary plasma thruster

Plasmas alter high-frequency electromagnetic signals primarily through stro ng electron density gradients or electron densities approaching the critica l plasma density. A plasma can potentially degrade electromagnetic systems through signal attenuation as well as increased amplitude or phase noise. T his paper reviews the physical mechanisms of a plasma which cause phase shi ft, attenuation, phase modulation, and amplitude modulation. To make predic tions of these effects, a general ray-tracing method is also reviewed and t hen applied to the localized high-speed plasma flow of a stationary plasma thruster (SPT). The SPT is currently being tested and considered for use ab oard next-generation spacecraft, where careful consideration must be given to possible interactions with satellite electromagnetic systems such as for communication, navigation, and remote sensing. The study also models the r ather significant plume impact to phase and amplitude for a range of freque ncies. A summary is provided of ray-tracing simulations characterizing both phase and amplitude effects at frequencies from 0.5 to 17 GHz and thruster axial positions from 0.25 m to 1.5 m, The results correlate well with know n data.